Monthly to
seasonal dynamical atmospheric prediction at CPTEC has been performed since
January 1995. The model used for these predictions is theCPTEC version of the COLA AGCM which was
derived from the NCEP model ( Kinteret
al. 1988) and includes the SSIB module (Xue et al. 1991). The horizontal
resolution of the AGCM CPTEC/COLAis
T62 and there are 28 levels in the vertical (Cavalcanti et al. 1995). The
seasonal predictions at CPTEC, during the first 3 years, were results of an
ensemble of 4 members, using 4 consecutive days as initial conditions. In 1998
there was an increase in the number of members, with the prediction based on 25
integrations. The application of boundary conditions also changed, from the use
of persisted SST anomalies, topredicted SST. In the tropical Pacific the SST is given by NCEP coupled
model forecast, and in the tropical Atlantic the SST is predicted using a
statisticalmodel (Pezzi et al. 1998).
Outside these regions persisted SST anomaliesare used.

Predictions for
the rainy season of Nordeste (Northeast of Brazil) in 1995 were discussed in
Nobre et al. (1995), and those for 1996, in Nobre and Cavalcanti (1996).
Results from simulations (with a T42L18 version of the model) of the Nordeste
rainy season of 1993 and 1994 using observed monthly Sea Surface Temperature
(SST) as boundary conditions and T42L18 compared well with observed values of
precipitation, and with NCEP reanalyses data (Cavalcanti et al. 1996).
Precipitation anomalies in Nordeste (area averaged 20S-120S;
450W-350W) from a simulation of 11 years (1986 to 1996),
using T42L18 reproduces much of the interannual variability in this region,
(Cavalcanti et al. 1998).The forecast
of the March-May 1998, 1999 and 2000 rainy season in Nordeste verified well.

Analysis of
systematic errors over Northeast South America show excessive precipitation on
the eastern Nordeste and deficit over Amazon river mouth, in MAM, as analysed
in a climatological simulation (Cavalcanti et al. 2001; Cavalcanti et al. 2000).
These errors are removed when the anomalies are calculated, and the interannual
variability over northern Nordeste is well represented in ten years simulation
(Marengo et al. 2001; Cavalcanti et al. 2000).

As usual, the
seasonal prediction at CPTECis
performed in two ways, one using persisted SST anomalies in all oceans and
another usingpredicted SST in the
Tropical Pacific and Atlantic Oceans and persisted SST anomalies in the other
areas. As the results were very similar, only the results using predicted SST
are shown. The model integrations at this month were performed using 18 initial
conditions. The predictions for bothDJF 2001/2002and MAM 2002 are
shown in Fig.1a,b. Above normal
precipitation is forecast for North and North-east South America, which
comprises eastern Amazonia and Nordeste.The higher values of positive anomalies observed over easternAmazonia in DJF are extended to areas of
Nordeste in MAM. To the south of this positive broad band there is a NW/SE band
of below normal precipitation, in DJF, located in the position of theSACZ.In MAM the prediction still showsnegative anomalies over southeast Brazil, but with reduced values. This
region has low predictability, showing large dispersion among members, opposite
to the north and northeast behaviour, where all members show the same sign of
anomalies (Fig. 2 a,b,c,d). The above normal
precipitation to the south of 300 S over South Atlantic is
associated with the positive novemberSST anomalies which are taken as boundary condition.

The prediction
taking into account the probability of dry, not dry, wet and not wet, following
IRI method ( Mason et al. 1999) is shown in Fig.3 a,b. It is seen high probability of wet conditions for the
north and northeast South America, except for the eastern coast, and high
probability of dry conditions for parts of the southern and south regions.
Normal conditions are predicted only for the extreme southwesternBrazil.

Monthly climate meetings at CPTEC are
conduced to analyse and discusse the monthly observed large scaleatmospheric and ocean conditions and the
model results. Considering the predictability of several regions of South
America,the intensity of the SST forcing,
and verifying the consistence with other GCMs, a seasonal prediction consensus
is performed based on the models results. In this month, the consensus
prediction was performed to JFM 2002 (Fig.4). In the
next issue of March, the MAM prediction for the Nordeste rainy season will be
updated.